Function strtoumax 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn strtoumax(
    nptr: *const c_char,
    endptr: *mut *mut c_char,
    base: c_int,
) -> uintmax_t

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/strtoimax.html.

Equivalent to strtoul() and strtoull(), except that the initial portion of the string shall be converted to uintmax_t.

Upon success, returns the converted value. If no conversion could be performed or the value of base is not supported, returns 0.